In gas turbine engines, liquid fuel is introduced into the combustion chamber either by means of fuel spray discharge system or by fuel vaporization system. In the fuel vaporization system, such as exemplified in the U.S. patents to Sneeden, U.S. Pat. No. 3,267,676, dated Aug. 23, 1966 and Sevcik, U.S. Pat. No. 2,884,759, dated May 5, 1959, fuel vaporizing tubes are employed without, or in conjunction with, caps to receive and admix fuel and air and, at least, partially effect vaporization of fuel. Heretofore, to convert an industrial stationary gas turbine engine, having a fuel vaporization system, from liquid fuel burning to the burning of gaseous fuel, such as natural gas, it has been necessary to disassemble the entire fuel feed system, including fuel nozzles or tubes and the liquid fuel manifold, and replace them with a new gaseous fuel manifold and fuel nozzles. This procedure, to take advantage of the availability and/or low cost of liquid and gaseous fuels, is complex, costly and results in relatively long shut-down periods for the engine during conversion. It also results, when conversion is made to gas, in lack of durability and reliability since the usual modifications frequently result in failure of the fuel nozzles due to fretting corrosion. This lack of durability resulted from wear of elements added in the modification for gas operation to effect a seal between the fuel-feed tube and the vaporizer fuel nozzle, which sealing elements were thought to be required for sustaining combustion of the gas.
Accordingly, it is an object of the present invention to provide, for a gas turbine engine, a dual-fuel feed system which can be converted quickly and easily from the burning of one of two fluid fuels to the other fluid fuel and back again.
Another object of this invention is to provide, for a gas turbine engine, a dual-fuel feed system in which the heretofore necessity for disassembly and reassembly and the accompanying relatively long shut-down to effect conversion of the gas turbine engine to the burning of a different fluid fuel is eliminated.
It is a further object of the present invention to provide a dual-fuel feed system for a gas turbine engine, which system eliminates the heretofore reduction in engine reliability as a result of the conversion from one fluid fuel to another.